This invention relates to a film unit withdrawing apparatus, and more particularly to an apparatus which automatically withdraws an exposed peel apart type instant film unit while permitting it to pass through a processing liquid spreading apparatus.
As is well known, a peel apart type instant film unit comprises a negative sheet, a positive sheet separately contained in a film pack, web means adapted to interconnect said two sheets in superposed relation when they are withdrawn from the film pack, and a pod holding processing liquid therein. In addition, a pull tab to be pulled out from the film pack prior to the withdrawal of the film unit is attached to a part of said web means. When a photograph is taken, a latent image is formed on the negative sheet. Thereafter, when the pull tab which normally projects outside the film pack is pulled, a film unit pull end at the leading end of the web means threads into a conventional pressure apparatus such as a pair of pressure rollers and is moved outward therebetween. As soon as said tab is torn off from the web means during this process, another pull tab attached to the next film unit to be used for the next photograph is caused to be projected into the pull position. The exposed film unit which is torn off the pull tab in the same manner as described in the foregoing, threads into the pressure apparatus by being pulled at its pull end projecting from the pressure apparatus. At this moment, the negative sheet and the positive sheet are brought into contacting superposed relation to each other, and simultaneously the pod is ruptured by the pressure apparatus and the processing liquid is spread between the two sheets. When the pull end is further pulled, the negative sheet and the positive sheet are intimately pressed together with the processing liquid spread between them by said pressure apparatus. During this process, the latent image on the negative sheet is transferred to the positive sheet as a positive image. When the negative sheet is peeled from the positive sheet after a predetermined fixing time, a photographic image is obtained on the positive sheet.
Heretofore, the above-described withdrawing operation of the peel apart type instant film unit has been manually conducted. However, there exist individual differences in the way such manual operation is performed. As a consequence, due to variations in the pulling direction of the tab, for example, the entrance angles of the pull end of the film unit are not constant at the time when the pull end of the film unit threads into the pressure apparatus, or due to differences of the pulling direction of the pull end of the film unit and of the pulling speed thereof, the film units are obliged to pass through the pressure apparatus under different conditions. As a consequence, the processing liquid is spread between the negative sheet and the positive sheet unevenly, which often results in an unacceptable quality of the photographic image to be produced on the positive sheet. Furthermore, if a camera including such film units is mounted, e.g., on a microscope for photographing, owing to the uneven pulling distance and speed, various forces tend to be exerted on the mounting portion between the microscope and the camera, and a loosening is likely to result there.